Processes employing chemical mechanical planarization (CMP) or polishing techniques have been widely used to planarize the surface of wafers during the various stages of device fabrication in order to improve yield, performance, and reliability of the fabrication process. In fact, CMP has become essentially indispensable for the fabrication of advanced integrated circuits.
Integrated circuits are chemically and physically integrated into a substrate by patterning regions in the substrate and layers on the substrate. To achieve high yields, it is usually necessary to recreate a substantially flat substrate after processing steps that leave topographic features on the surface of the wafer, features such as surface irregularities, bumps, troughs, and trenches.
One type of commonly used pad for applications such as polishing and CMP of substrates is a felt pad. The felt pad is a composite of fibers impregnated with a resin. Felt pads offer many unique advantages compared to non-fiber pads like pure polyurethane pads. Some examples of the advantages are low cost of ownership and good non-uniformity for the CMP process. However, for some applications, felt pads may not be the ideal choice. Particularly, felt pads may not be able to provide optimum performance for applications such as those that require good planarization.
A need remains for improved polishing pads which provide effective planarization and improved planarization efficiency for substrates such as electronic device substrates. In addition, there is a need for new pads that can be used for longer periods of time before the pad must be replaced: in other words, pads having longer operational life for processes such as CMP.